1. Field of the Invention
This invention relates generally to information signal processing and in particular to the field of processing time sequential information signals such as video signals for the purpose of compressing the amount of information to be transferred from an encoding site to a decoding site, as in transmitting color video imaging signals over hard wire intra-system lines or telephone lines.
2. Prior art
The prior art is summarized by U.S. Pat. Nos. 4,816,901 to J. Music et. al. for a METHOD AND SYSTEM FOR COMPRESSING COLOR VIDEO DATA, March 89; and 4,847,677 to J. Music et. al. for VIDEO TELECOMMUNICATION SYSTEM AND METHOD FOR COMPRESSING AND DECOMPRESSING DIGITAL COLOR VIDEO DATA, July 89.
In the prior art, a three step block coding system for the efficient encoding of TV signals usually involves sampling, transformation and quantization. The transformation step, which most commonly uses the Discrete Cosine Transform method, is a computation-intensive procedure involving matrix multiplication. The intensity of this computational procedure, especially where realtime coding is required, greatly increases the complexity of practical coding schemes.
In order to preserve the spatial resolution and high frequency components of a Television signal it is necessary to sample at a high rate, usually twice the highest frequency component of the signal. In the case of standard broadcast television, this is a sample rate of around 9 megahertz. This results in approximately 500 samples per horizontal scan line and about 120,000 samples per TV field or 240,000 samples per TV frame. If each sample is 15 bits, this results in about 3.6 million bits per frame or 108 million bits per second.
The bit rate must be reduced for applications planned for the future.